Scott Brown and Andrew Loupe set the pace for the first 18 holes of the 2016 Farmers Insurance Open, shooting identical six-under-par 66s that pushed them one shot ahead of five players who tied for third place.
Interestingly, most of the low scores Thursday came from the North Course at Torrey Pines, with Brown being the only player among the top seven to play the South Course. K.J. Choi and Chesson Hadley were the only other players in the top 14 who played the South Course.
Here's how the full leaderboard at this year's Farmers Insurance Open looks heading into Friday:
Loupe has been an all-or-nothing player so far this season, as Sean Martin of PGATour.com noted:
So far, the 27-year-old is on his way to his fourth top-10 finish. There is still a long way to go, but Thursday marked his fifth straight round with a score of 68 or lower.
Billy Horschel, who is among the five players tied for third place, needed a strong rebound performance after missing the cut at last week's CareerBuilder Challenge. He made it to the third round of that event, but a 75 on Saturday sent him home early.
Thursday's performance was in line with how Horschel played at the Hero World Challenge in December, when he had three rounds under par. He will need to start showing consistency to end his 16-month winless drought.
Moving down the leaderboard, Phil Mickelson continued to look strong. Lefty is three under par after 18 holes, and a lot went right for him, such as this tee shot on No. 8, courtesy of the PGA Tour:
Things got better for Mickelson, who showed off his long game on the par-five 13th hole, courtesy of the PGA Tour:
The 13th hole was the starting point for Mickelson's run in the first round. He made three straight birdies from Nos. 13 through 15 to climb within shouting distance of Brown atop the leaderboard.
Mickelson started his year off on the right foot at the CareerBuilder Challenge, tying for third with a 72-hole score of 21 under par, his best score in a tournament since the 2013 Waste Management Open.
Martin took it back further to find the last time Mickelson had performed this well on the South Course at Torrey Pines:
Mickelson gave one of those birdies back with a bogey on No. 17 but finished strong with a birdie on the final hole to keep his score under 70.
Even though he can be an erratic player because of his risk-taking tendencies, this is a great way for him to begin his season. A victory at the end of the weekend would be nice, but playing three more rounds under par wouldn't be a bad consolation.
Dustin Johnson finished one shot behind Lefty with a two-under-par 70.
Johnson needed a late rally to remain two under, including this shot from just off the green on No. 17 for par, per the PGA Tour:
Even without a victory to his name, Johnson is showing great consistency with three top-15 finishes in his last three tournaments. He got off to a slow start three weeks ago at the Hyundai Tournament of Champions with an opening-round 73 before breaking 70 in the next three rounds.
If Johnson follows that same path this weekend at Torrey Pines, he's going to put himself in contention for his first victory since March 2015.
Picking a favorite after 18 holes is difficult because many players are capable of posting low scores Friday. Brown and Loupe don't have extensive resumes on the PGA Tour, so they have to prove Thursday's performances weren't flukes.
The large group that is one shot behind Brown and Loupe will put pressure on the leaders, and Mickelson found his groove late to build momentum heading into the second round.
Thursday was a strong day for players on the North Course, so look for the big movers Friday to come from that area at Torrey Pines.